What do you think of my drawing?

your poses are really stiff and i suggest you practice doing gesture drawings. like go outside and draw people passing por and draw them in like 10 segundos because that will really challange you to capture poses and movement quickly.
also, spines curve, bodies are curvy, don't be afraid to draw things a little bit curvy (sorry i cant seem to draw today or ever so the drawing below is shit but i hope it gets the point across)

(don't get me wrong tho its still a good drawing you just need to work on the fundamentals)

it's really nice

Really good, but I guess I don't really know who they are.

Constructive criticism: they are good just make your lines a little smoother so the people look like they flow.

central is definitely best...try some shading...like such...

That looks really good. :)